The use of synthetic cutting fluid compositions has grown rapidly. The oil-free compositions are designed to impart lubricity at high temperatures, inhibit rust, reduce surface tension, produce low foam and be compatible with concentrated electrolyte solutions for hard water.
Examples of synthetic metal working fluid compositions which may be both oil and water soluble are those formed from conventional non-ionic surfactants which consist of a hydrophobe which has been polyoxyethylated. Such non-ionic surfactants have been provided with a phosphate radical which improves several of the sought for characteristics including increasing the hydrophilic characteristic of such surfactants. Examples of such metal working fluids are the ANTARA.RTM. lubricant compositions which are sold by the GAF Corporation. These metal working fluid compositions are based on aliphatic and aromatic hydrophobic moieties which are further alkoxylated and phosphated.
The present invention provides compounds particularly suitable for use in formulating synthetic aqueous based metal working fluids. The compounds are phosphated, polyethoxylated (2-10 EO) n butane 1,4 diols. They are completely hydrophilic in nature. They do not contain any hydrophobic moiety. The particularly novel aspect of the present invention resides in phosphoric acid esters of the condensation products of one mole of butane-1,4-diol with from 2 to 10 moles of ethylene oxide. These esters are useful in a variety of applications such as synthetic aqueous based metal working fluids. Other uses are as lubricating additives, corrosion inhibitors, hydraulic fluids, flame retardant additives, plasticizers and the like. The phosphate esters of the present invention may be represented as follows: ##STR1## wherein X is a member selected from the group consisting of H and polyoxyethylbutanol having the general formula: ##STR2## such that the compound can be either a mono-, di- or tri-ester of phosphoric or polyphosphoric acid, or mixtures of the three, m and n are positive integers of 1 or higher. In the case where m and n are greater than 1, their values are similar to the degree of polymerization occuring in polyphosphoric acid; q and p are positive integers the total of which is from 2 to 10 and wherein z is also an integer having a value of 1 or higher.
An examination of the general formula set forth above discloses a straight chain molecule which contains no branched chains. The component moieties of the compound are individually hydrophilic and in combination remain hydrophilic. This is believed to particularly distinguish the compounds of the present invention from those found generally available which are based on combinations of hydrophobic and hydrophilic moieties. The straight chain nature of the present compounds indicates a further characteristic that is particularly desirable that of being biodegradable. The compounds of the present invention may be further modified by forming ammonium, substituted ammonium, alkali metal or alkaline earth metal salts thereof.
The preparative methods for synthesizing the rather complex compounds and mixtures thereof of the invention follow well known synthetic procedures. The ethyoxylation is carried out by adding a pre-determined number of moles of ethylene oxide to the terminal hydroxyl groups of the butanediol. It is understood that this addition results in a well known random distribution of oxyethylene groups on either side of the butanediol moiety. The phosphation is also carried out by well known methods. The phosphating agent preferred in the present invention is polyphosphoric acid although P.sub.2 O.sub.5 may also be used. The choice between the two phosphating agents depends upon whether a proponderance of diester or monoester is preferred. Polyphosphoric acid produces more monoester while P.sub.2 O.sub.5 produces more diester.
Typical preparative methods used in the present invention were as follows:
n Butanediol is charged into a pressure vessel such as an autoclave. 0.05% NaOH catalyst based on the diol is added. A predetermined amount of ethylene oxide is charged into a cylinder which is coupled to the pressure vessel by means of a valved pipe. The valve is opened to permit the reaction to proceed at a pressure of 30 to 33 psig with the temperature controlled to 130.degree. to 140.degree. C. The reaction continues until the pressure drop indicates no unreacted ethylene oxide remains.
Phosphation of ethoxylated n butanediols may be carried out using P.sub.2 O.sub.5 or polyphosphoric acid (PPA) of 115% strength. The phosphation was carried out in a four-necked flask which is equipped with a mechanical stirrer, a thermometer, an N.sub.2 inlet (or CaCl.sub.2 tube) and a vent tube (or a condenser). Prior to phosphation a color stabilizer may be added to the diol ethoxylate in amounts of 0.5 to 1 g. The stabilizer is hypophosphorous acid when P.sub.2 O.sub.5 is used and sodium hypophosphite when PPA is used.
P.sub.2 O.sub.5 is added in portions while holding the temperature to about 50.degree.-60.degree. C. Upon completion of the addition the reactants are heated for about five hours at 90.degree.-95.degree. C.
PPA in a predetermined amount is placed in a dropping funnel which was provided to one neck of the flask. The PPA was added dropwise maintaining the temperature at 40.degree. to 45.degree. C. Upon completion of the addition the reactants are heated for about two hours at 95.degree. to 100.degree. C.
The products of either phosphation may be bleached using 1 to 3 ml of 30% H.sub.2 O.sub.2.
Typical preparations are shown below.
__________________________________________________________________________ PREPARATIONS Temp. During Diol Phosphating Agent Addition Reaction Temp. No. g., Moles g., Moles (Time of Add.) (Time of Reaction) Yield g. % Monoester % Diester __________________________________________________________________________ 1 B1D.4EO P.sub.2 O.sub.5 50.degree.-60.degree. C. 90.degree.-95.degree. C. 133, 0.5 55, 0.37 (30 min.) (5 hrs.) 188 44.5 65.4 2 B1D.6EO P.sub.2 O.sub.5 60.degree.-65.degree. C. 90.degree.-95.degree. C. 177, 0.5 55, 0.37 (30 min.) (5 hrs.) 232 41.0 50.0 3 B1D.6EO PPA 50.degree.-55.degree. C. 95.degree.-100.degree. C. 354, 1. 340, 2. (25 min.) (2 hrs.) 694 71.9 13.4 4 B1D.6E0 PPA 40.degree.-45.degree. C. 95.degree.-100.degree. C. 354, 1. 170, 1. (30 min.) (2 hrs.) 524 47.8 11.1 5 B1D.6EO PPA 40.degree.-45.degree. C. 95.degree.-100.degree. C. 354, 1. 127, 0.75 (20 min.) (2 hrs.) 481 49.0 0.0 6 B1D.6EO PPA 40.degree.-45.degree. C. 95.degree.- 100.degree. C. 354, 1. 85, 0.5 (20 min.) (2 hrs.) 439 35.6 3.1 7 B1D.6EO P.sub.2 O.sub.5 60.degree.-65.degree. C. 90.degree.-95.degree. C. 177, 0.5 26, 0.185 (20 min.) (5 hrs.) 232 45.4 45.7 __________________________________________________________________________
The compounds of the present invention are all based on butanediol which for convenience sake will be indicated as B1D. The moles of ethylene oxide with which one mole B1D is ethyoxylated will be indicated as a number of EO and the phosphating agent will be indicated as P.sub.2 O.sub.5 or PPA for polyphosphoric acid. The ratio shown following the butanediol, ethylene oxide and phosphating agent indicates the ratio between 1 mole of the ethoxylated butanediol and the moles of phosphating agent with which it has been reacted.
The compounds of the present invention are all based on B1D. The degree of ethoxylation varies between 2 EO to 10 EO, and the phosphation may be of varying degrees with either PPA or P.sub.2 O.sub.5. The compounds falling within those described by such ratios are all suitable for use in synthetic metal working fluid compositions sometimes called coolants. When the compounds are diluted with water, they form true solutions. The compounds further produce little or no foam and such foam as may be produced is of a quick breaking character. The compounds of the invention further provide corrosion protection to most metals. They further stand up well under extreme pressure and elevated heat.
The desirable qualities of the ethoxylated phosphated butanediols of the present invention are demonstrated by comparison with two commercially available compounds used in preparing metal working fluid compositions. ANTARA.RTM. LP-700 is a phosphate ester of phenol plus 6 EO reacted with one mole of P.sub.2 O.sub.5 for each 2.7 moles of the ethoxylated phenol. ANTARA.RTM. LK-500 is the phosphate ester of n C.sub.6 H.sub.13 OH+3.4 EO and phosphated using 1 mole of P.sub.2 O.sub.5 for each 2.7 moles of the ethoxylated alcohol.